Does the ad give you the diameter? That would go a long way to narrow it down.
I don't think it's an Aerostar - they branded their name prominently and there isn't a nose cone; it's a ring like a parachute or whatever. That's a distinguishing feature that should help you identify it. Vergnet?
That said, I tried looking up alternatives and they don't resemble this any more than the Aerostar. Modified Aerostar?
Paul Gipe's book has an appendix with dozens of WT's in it, many in this size range. Some names you can chase down:
Vergnet
Aerocraft
Sunrise
Gaia
Kramer
The list in Gipe's book doesn't have pictures so I can't tell if some of these are even downwind 2-bladers or not. But they are in the size range (10-15 meters). I did some quick google searching and didn't turn up an obvious ringer for this one. See if you have more luck...
